The delivery of broadband data communications services, such as Internet traffic, telephony, broadcast TV and video-on-demand, to homes and business over existing power distribution systems is very attractive to content service providers as well as their customers. The power distribution systems can constitute, for example, a power distribution network that delivers energy to homes and businesses, a power distribution system within a multiple dwelling unit (“MDU”) or a multiple tenant unit (“MTU”), such as a hotel or an apartment building, or any other power network environment where access to the transmission media for the purpose of the data or content delivery is shared in accordance with time division multiplexed access (“TDMA”) techniques. A power line communications (“PLC”) system, which can carry both power and communications signals, is a highly desirable communications signal distribution network because it usually already exists at locations where communications services are desired and does not require the installation of additional cables. As a result, the use of a PLC system to provide communications services can lead to a tremendous savings in installation costs, which in turn can translate into lower costs for services to the end customer.
Many prior art PLC systems operate in accordance with a point to point communications method where a plurality of PLC transceiver devices communicate with one another over the power line media in an ad hoc fashion, similarly as typically occurring in a lateral access network (“LAN”). As such, system complexity is required to support transmission detection and synchronization for each PLC device in the network. In such PLC systems, all of the PLC devices normally share the available communications bandwidth somewhat equally and symmetrically. In addition, some of these prior art point to point PLC systems need to implement data priority methods to handle cases of contention and bandwidth saturation.
Some prior art PLC systems are arranged in the form of a point to multipoint network configuration where the primary objective is distributing broadband data or content to destination PLC devices located in homes, businesses, MDUs or MTUs. In the point to multipoint network configuration, a main, or head-end, PLC transceiver typically is the source or distribution point of broadband data and communicates with a plurality of end point, or remote, PLC transceivers, which are destinations for the bulk of the broadband data transmitted from the head-end. Ordinarily, the data flow between the head-end and the remotes is asymmetric, where the bulk of the data is transmitted downstream from the head-end to the remotes.
The use of adhoc or asynchronous communications methods for transmission of PLC signals in a point to multipoint network, however, has several drawbacks. First, adhoc administration of communications involves an overhead associated with media access and node synchronization and also can result in increased latency, which can degrade the quality of communications services being provided. Furthermore, networks that operate based on adhoc types of media access typically show a considerable degradation in bandwidth utilization as the number of communication nodes increases. In addition, as each of the remotes is typically utilized by a different customer located within a same point to multipoint network, the decoding of all PLC signals present on the PLC network by each of the remotes creates difficulties in maintaining isolation and security between the remotes. Consequently, in many prior art point to multipoint PLC systems, data distributed to one customer from the head-end is not isolated and protected to prevent other customers on the same network from accessing the data.
Therefore, a need exists for a system and method for efficiently utilizing available bandwidth for PLC signal transmissions between a head-end PLC transceiver and remote PLC transceivers in a point to multipoint PLC system configuration and also for isolating remotes from one another, reducing latency and simplifying data synchronization processing in point to multipoint PLC systems.